Comments on “Unsaturated soils: From constitutive modelling to numerical algorithms” by Daichao Sheng,Antonio Gens,Delwyn G. Fredlund and Scott W. Sloan, [Computers and Geotechnics 35(6) (2008) 810–824]

Exploration is made on a simplified soil–water characteristic relation introduced by Daichao Sheng et al. Possible derivation of this relation is analyzed to introduce its reasonable relation. Further exploration shows that both relations result in disagreement with experiments. The disagreement arises from the replacement of water term with suction term in the differentiating expression of volumetric water content.     

A 2.5-D coupled FE–BE model for the dynamic interaction between saturated soil and longitudinally invariant structures

A two-and-a-half-dimensional (2.5-D) coupled finite element–boundary element (FE–BE) model is presented to simulate the three-dimensional dynamic interaction between saturated soils and structures with longitudinally invariant geometries. A regularized 2.5-D boundary integral equation for saturated porous media is derived that avoids the evaluation of singular traction integrals. The 2.5-D coupled FE–BE model is established by using the continuity conditions on the soil–structure interface. The developed model is verified through comparison with an existing semi-analytical method. Two case studies of a tunnel embedded in a poroelastic half-space and the efficiency of a vibration isolating screen are presented.     

Influence of model type,bias and input parameter variability on reliability analysis for simple limit states in soil–structure interaction problems

ABSTRACT

A general closed-form solution for the true probability of failure of a simple limit state function with one load term and one resistance term is derived. The formulation considers contributions due to model type, uncertainty in method bias values, bias dependencies, uncertainty in estimates of nominal values for correlated and uncorrelated load and resistance terms, and average margin of safety expressed as the operational factor of safety. Example calculations are presented using different load and resistance models for the pullout internal stability limit state of steel strip reinforced soil walls together with matching bias data reported in the literature.